Well, you probably don't want to hear this but Ellie is 7.5 and while she knows where she is supposed to go, she sometimes doesn't want to wait for me to take her out, so she goes wherever she wants. And yes, I do take her out usually at least five times a day but she just has her own schedule I guess.
I expect that this will go on forever...
You may want to reconsider allowing your pup to be outside unsupervised. Some of us won't even let our adults out alone. There are just too many dangers.